Tool and an effector

ABSTRACT

An effector comprises a pair of opposing jaws directly mounted on a keeper so that the jaws are pivotable about the keeper. The jaws are connected to an actuating member within the keeper, so that translational movement of the actuating member causes the jaws between an open and closed position.

BACKGROUND OF THE INVENTION

The present invention relates to an effector and to a tool, and particularly, but not exclusively to a surgical tool and an effector therefor.

A known form of surgical tool has an effector mounted at the end of a shaft. The effector has two jaws and is actuated by an actuating member in the shaft. The jaws are pivotally attached to one another scissor fashion by means of a pin joint. The pivotal end of each jaw is attached to a respective ink by a further pin joint. The links attached to the jaws are attached to one another and to the actuating member in the shaft by means of a still further pin joint. Translational movement of the actuating member in the shaft causes the links to move in a scissor-like manner so that the jaws open and close. When the jaws are closed, the jaws, links and actuating member are aligned, axially of the shaft. However, when the jaws are fully open the links and the pivotal ends of the jaws project laterally beyond the diameter of the shaft.

This lateral projection of the links and jaws beyond the diameter of the shaft is undesirable since the tissue of the patient may be caught in the links and jaws of the tool. Furthermore, the pins of the pin joints are very small, so that it is difficult to install the pins securely. The small size of the pins also means that they are very prone to fracture. Again, such fractures are obviously undesirable since they result in the introduction of foreign material into the patient. The mechanical advantage of the tool also varies according to the position of the jaws. As the jaws approach the closed position, the mechanical advantage of the system is greatly reduced in comparison with the mechanical advantage when the jaws are in the fully open position.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a tool in which the above disadvantages are overcome.

The invention provides an effector as claimed in claim 1 and a tool as claimed in claim 17.

An embodiment of the invention will now be described with reference to the drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exploded perspective view of a tool in accordance with the invention;

FIG. 2 shows a perspective view of one half of the effector of the tool of FIG. 1 in a closed position;

FIG. 3 shows a perspective view of one half of the effector of the tool of FIG. 1 in an open position;

FIG. 4 shows the tool of FIG. 1 in the closed position; and

FIG. 5 shows the tool of FIG. 1 in the open position.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In FIG. 1, a surgical tool 1 has an effector 2, a pull rod 3 and a tube 4. The effector 2 comprises a pair of jaws 5 a, 5 b, a keeper 6 and an actuating member 7. The keeper 6 is divided along a plane of separation of the jaws 5 a, 5 b A—A to form two identical keeper parts, 6 a and 6 b. The effector 2 is rotationally symmetrical about the plane of separation of the jaws A—A. Each jaw 5 a, 5 b is associated with a respective keeper part 6 a or 6 b. The jaw 5 a has an operational portion 8 which is used to carry out surgical procedures and an actuating portion 9, where the movement of the jaw is controlled. The outer surface of the operational portion 8 of the jaw 5 a is smooth, while the inner surface of the jaw 5 a may be serrated or uneven. The lower surface of the actuating portion 9 has pivoting means in the form of a notch 10 engageable with pivoting means in the form of a corresponding rib 11 on the keeper part 6 a so that the jaw 5 a may be pivoted about the rib 11 on the keeper part 6 a. The rib 11 is arranged on the inner surface of the keeper part 6 a. The notch 10 and the rib 11 are arcuate to facilitate pivotal motion of the jaw 5 a about the keeper part 6 a.

The actuating member 7 has an arm 12 a projecting from its lower end in the direction of translational movement of the actuating member 7 and an actuating arm 12 b projecting from its upper end, also in the direction of translational movement of the actuating member 7. Projections 13 a and 13 b are located at the end of the respective arms 12 a and 12 b, so that the arms 12 a and 12 b are slidable within a recess (see below) in the keeper parts 6 a and 6 b respectively and the actuating member 7 may thus be located in the keeper parts 6 a and 6 b. The projections 13 a and 13 b also permit engagement of the respective jaws 5 b and 5 a, so that the actuating member 7 can actuate the jaws 5 a and 5 b.

The jaw 5 a has actuating means, arranged on an opposite side of the plane of separation of the jaws A—A to the jaw pivoting means, in the form of a recess 14 on the upper surface of the actuating portion 9. The recess 14 is engageable with actuating means in the form of the projection 13 b on the actuating member 7 so that the jaw 5 a may be actuated by the actuating member 7. The recess 14 and the projection 13 b are arcuate in cross-section to permit pivotal motion of the jaw 5 a around about the projection 13 b. The keeper part 6 a has a recess 15 adjacent the rib 11 for clearance of the projection 13 a on the arm 12 a of the actuating member 7 in the keeper part 6 a. When the actuating member 7 is inserted in the keeper part 6 b, the projection 13 b engages in the recess 14 so that the top surface of the projection 13 b is flush with the top surface of the actuating portion 9.

The pull rod 3 is also attached to the actuating member 7 so that the pull rod 3 may actuate the actuating member 7. The actuating member 7 may have a threaded bore and the pull rod 3 may be threaded so that the pull rod 3 and actuating member 7 can be connected together by means of the interengaging threads. Alternatively, the actuating member 7 may be moulded around serrations adjacent the end of the pull rod 3.

FIGS. 2 and 3 show the actuating member 7 arranged in the keeper part 6 a. The jaw 5 a is also arranged on the keeper part 6 a. The opposing jaw 5 b (not shown) is arranged on the keeper part 6 b in a similar manner. The actuating portion 9 of the jaw 5 a is laterally offset from the actuating portion of the jaw 5 b so that the actuating portions of the jaws 5 a and 5 b are located side by side in the keeper 6. When the jaws 5 a, 5 b, the actuating member 7 and the pull rod 3 are assembled in the keeper 6, the tube 4 is: slid over the keeper 6 to hold the assembly together and constrain radial movement of the components in the keeper 6. It is also desirable to constrain axial movement of the assembled components. The keeper parts 6 a and 6 b illustrated in the embodiment shown in FIGS. 1 to 3 have a groove 16 around their outer surface. When the tube 4 has been placed over the assembled components, the tube may be deformed around the groove 16 so that axial movement of the assembled components may be constrained. Alternatively, the outer surface of the keeper 6 may simply be bonded to the inner surface of the tube 4 to constrain axial movement of the keeper. It is also possible to include a resilient element on the keeper 6, for example, a pip or spring-loaded ball catch which engages a through hole in the tube 4, or vice versa, to constrain axial movement of the assembled components.

FIG. 2 shows one half of the assembly when the jaw 5 a is in a closed position. In the closed position the pull rod 3 and actuating member 7 are in a retracted position. The jaw 5 a rests on the rib 11 so that the jaw extends substantially parallel to the plane of separation of the jaws A—A. When the pull rod 3 is actuated so that it and the actuating member 7 move translationally within the keeper part 6 a towards the jaw 5 a, the projection 13 b on the actuating member 7 pushes the jaw 5 a, causing it to pivot about the rib 11 in a clockwise direction so that the jaw 5 a opens (see FIG. 3). The pull rod 3 may be actuated by a variety of means, for example, by means of the actuator disclosed in UK patent application No. 9902647.8. It will be appreciated that the opposing jaw 5 b (not shown) is pivoted in a similar manner in an anti-clockwise direction. The jaws 5 a and 5 b can be closed again by actuating the pull rod 3 and thus the actuating member 7 in the opposite direction so that they return to the retracted position.

FIGS. 4 and 5 show respectively the position of the jaws 5 in the open and closed positions. It will be seen that even in the open position there are no components, with the exception of the jaws 5 a and 5 b themselves, protruding beyond the diameter of the tube 4, and the outer surface of the jaws is smooth. The risk of the tool catching on tissue of the patient is, therefore, minimised.

It will also be seen that the components are arranged in the tube 4 in such a way that it is very difficult for fluids and other matter to enter the tube 4. Although the tool of the present embodiment is designed to be disposable, it may also be used as a re-usable tool.

It is thus desirable for the fluids and other matter entering the tube 4 to be kept to a minimum to aid re-sterilisation.

The mechanical advantage of the tool is substantially constant over the range of movement of the jaws. The fact that the recess 14 and notch 10 are located on opposite sides of the plane of separation of the jaws means that the mechanical advantage of the tool is also maximised.

The components of the tool may be made of a variety of materials. For example, the tube may be made of stainless steel or titanium alloy, whereas the jaws may be made of plastics or metal.

Different jaws may be used for different applications. For example the jaws may be forceps, where gripping is required. However, the jaws may also be scissors or spreaders respectively where cutting and spreading is required. Although the tool has been described in the context of surgical use, it will be appreciated that the tool may be used in many other fields where delicate handling of materials is required, for example in the electronics industry, botany or entomology. 

What is claimed is:
 1. An effector comprising a pair of opposing jaws directly mounted on a keeper and pivotable thereabout, the jaws being connected to an actuating member within the keeper, so that translational movement of the actuating member causes the jaws to pivot between an open and closed position, wherein each jaw has pivoting means engageable with respective pivoting means on the keeper and actuating means engageable with corresponding actuating means on the actuating member, the jaw actuating means and the jaw pivoting means being arranged at opposite sides of a plane of separation of the jaws.
 2. An effector as claimed in claim 1, wherein the pivoting means comprise corresponding notches and ribs.
 3. An effector as claimed in claim 2, wherein the notches are arranged on the jaws and the corresponding ribs are arranged on the keeper.
 4. An effector as claimed in claim 2 or claim 3, wherein the notches and ribs are arcuate.
 5. An effector as claimed in claim 1, wherein the keeper comprises at least two parts, one part being associated with each jaw.
 6. An effector as claimed in claim 1, wherein the actuating member is connectable with a pulling rod.
 7. An effector as claimed in claim 6, wherein the actuating member is connectable with the pulling rod by means of interengaging threads.
 8. An effector as claimed in claim 1, wherein the actuating means comprise corresponding projections and recesses.
 9. An effector as claimed in claim 8, wherein the recesses are arranged in the jaws and the projections are arranged on the actuating member.
 10. An effector as claimed in claim 8 or 9, wherein the projections and recesses are arcuate.
 11. An effector as claimed in claim 1, wherein the jaws are forceps, scissors or spreaders.
 12. An effector as claimed in claim 1, wherein the jaws are made of plastics or metal.
 13. An effector as claimed in claim 1, wherein the effector is rotationally symmetrical about the plane of separation of the jaws.
 14. A tool comprising the effector as claimed in claim 1, a pull rod connected to the actuating member, and a tube surrounding the effector and the pull rod.
 15. A tool as claimed in claim 14, wherein the pull rod is moulded around the actuating member.
 16. A tool as claimed in claim 14 or 15, wherein the keeper is held within the tube by deformation of the tube around the keeper so that axial movement of the effector within the tube is constrained.
 17. A tool as claimed in claim 14 or 15, wherein the keeper is held within the tube by bonding so that axial movement of the effector within the tube is constrained.
 18. A tool as claimed in claim 14 or 15, wherein the keeper has resilient projections or notches engageable with corresponding notches or resilient projections in the tube, so that axial movement of the effector within the tube is constrained.
 19. A tool as claimed in claim 14, wherein the tool is disposable.
 20. An effector as claimed in claim 1, wherein the keeper is divided along a plane of separation of the jaws to form two identical keeper parts. 